This present invention relates to vehicle navigation or route guidance systems and more particularly to a navigation system that indicates an upcoming maneuver at a predetermined interval from the upcoming maneuver.
Navigation systems generally provide a recommended route from a starting point to a desired location. Generally, the starting point and desired location are selected from a large database of roads stored in a mass media storage, such as a CD ROM, which includes the roads in the area to be traveled by the user. The navigation system can be located in a personal computer or it can be installed in a vehicle. If the navigation system is installed in a vehicle, the starting point is typically the current position of the vehicle, which can be entered into the navigation system by an associated position determining system that usually includes a Global Positioning System (GPS) receiver.
The navigation system determines a route from the starting point to the destination utilizing an algorithm well-known to those in the art and currently in use in many navigation systems. Usually there are many potential routes between the selected starting point and the desired destination. Typical navigation systems select a recommended route based upon certain predetermined criteria including the length of the route and the estimated time of travel on the route. Depending upon the predetermined algorithm of the navigation system, the navigation system will recommend the route with the shortest total length, the lowest total time, or some weighted average of length and time.
The recommended route is then displayed to the user as a map showing the starting point, desired destination and highlighting the recommended route. Preferably, if the navigation system is installed in a vehicle, the navigation system displays the current location of the vehicle and provides turn-by-turn instructions to the driver, guiding the driver to the selected destination along the recommended route. The indication of the upcoming maneuver may be indicated audibly, such as with a voice description of the upcoming maneuver, or displayed visibly, or both.
It may be necessary for the vehicle to change lanes prior to the maneuver because the maneuver could include exiting a highway, entering a highway, or making a turn at an intersection. Therefore, the upcoming maneuver is indicated to the driver at a distance before the maneuver so that proper vehicle positioning can be accomplished. Depending upon the type of vehicle in which the navigation system is installed, this distance may be inadequate or too long. For example, larger vehicles, such as buses, will require more time to achieve a proper position to perform the upcoming maneuver than a small car would.
This problem is further complicated by the desirability to create navigation systems which can be easily moved from one vehicle to another, because drivers typically own more than one type of vehicle. For example, a driver may own a small vehicle for commuting to and from the workplace and the driver may also own a large motor home for vacationing or a truck that has the capability of pulling a trailer. The motor home and the truck with a trailer will require additional time and distance to be in the proper position to make the upcoming maneuver as compared to the time and distance needed by the small vehicle or the truck without the trailer.
Accordingly, it is desirable to provide a navigation system that indicates an upcoming maneuver at a predetermined distance from the upcoming maneuver based on vehicle type. It is also desirable to provide a navigation system that is simple for a driver to adjust to navigate for a different vehicle type so that the navigation system can be easily moved from one vehicle to another.